Common childhood infections: Bacteria

Question 1

Name two bacteria that cause harm via their exotoxins [2]

Answer 1

Diphtheria: Corynebacterium diphtheriae

Cholera: Virbrio cholerae

Question 2

Describe how Vibrio cholera causes diarrhoea by the exotoxin produced by the pathogen

Answer 2

Induces diarrhoea by:
- A-B toxin
- A part activates cell’s G-protein, modifies G-protein and keeps it in active state
- causes more and more production of adenylate cyclase: causes more cAMP
- this stimulates CFTR channel to have more Cl- leave cell: imbalance of electrolytes
- water follows Cl- and electrolytes
- causes severe d

Question 3

Describe pathophysiology caused by Corynebacterium diphtheriae

• What process does the A-B subunit inhbit? [1]
• What are the pathological consequences for the heart [2] & nerves? [3]
• What structural change occurs in mouth? [1]

Answer 3

Diphtheria toxin: A and B subunits inhibits protein synthesis:

Heart implications:
- Myocarditis
- Heart block

Nerve implications:
- Difficulty swallowing
- Paralysis
- Diplopia

Get pseudomembrane in mouth

Question 4

What are symptoms of infection of Corynebacterium diphtheriae infection [3]

Answer 4

Symptoms:
- Sore throat
- Fever
- Pseudomembrane (grey membrane at back of throat: obstructs resp. tract)

Question 5

What are the three cocci gram +ve organsims need to know? [3]

Answer 5

Staphylococcus
Streptococcus
Enterococcus

Question 6

Which part of the LPS membrane of bacteria is toxic? [1]

When is this released? [1]

Answer 6

Lipid A

Released during lysis of organsim

Question 7

Meningococcal disease describes infections caused by the bacterium []

Answer 7

Meningococcal disease describes infections caused by the bacterium Neisseria meningitidis

Question 8

Which two molecules are activated by LPS that cause inflammatory cascade for meningococcal disease? [2]

Answer 8

IL-6
TNF-α

Question 9

Describe the pathogenesis of meningococcal disease

Answer 9

Question 10

What is the definiton of fever? [1]

How do the following differ from rectal temp [3]

• Ear
• Mouth
• Armpit

Answer 10

Temperature > 38oC

Ear: similar to rectal
Mouth: 0.5 lower than rectal
Armpit: 1 degree lower

Question 11

Why do babies under 3 months get thoroughly teseted (blood tests, lumbar puncture, and x-rays) if have a fever? [2]

Answer 11

High suspicion of index because need to rule out sepsis and meningitis

Question 12

Name three most common causes of septicaemia and meningitis [3]

Answer 12

Streptococcus pneumoniae

Neisseria meningitidis
* Group B and C
* Increase in Group W since 2009
* Teenagers, university students

Haemophilus influenzae B (HiB)

Question 13

Why are young infants so vulnerable to infection? [1]

Answer 13

Young infants are not fully vaccinated – why they’re still vulnerable

Question 14

Which vaccines are administered at 8 weeks old?

Answer 14

Diptheria, Tetanus, pertussis (whooping cough), polio, Haemiphilus influenzae type B & and Hep B

Meningococcoal group B

Rotavirus (gastroenteritis)

Question 15

Which vaccines are administered at 12 weeks old?

Answer 15

Diptheria, Tetanus, pertussis (whooping cough), polio, Haemiphilus influenzae type B & and Hep B

Pneuomococcal

Rotavirus

Question 16

Which vaccines are administered at 16 weeks old?

Answer 16

Diptheria, Tetanus, pertussis (whooping cough), polio, Haemiphilus influenzae type B & and Hep B

MenB

Question 17

Which vaccines are administered at 1 year old? [6]

Answer 17

Haemophilus influenzae type B, MenC

Pneumococcal

MMR

Men B

Question 18

What are the three cocci gram +ve organsims need to know? [3]

Answer 18

Staphylococcus
Streptococcus
Enterococcus

Question 19

Which of the following causes “Pneumococcus”

Staphylococcus
Streptococcus
Enterococcus

Answer 19

Staphylococcus
Streptococcus
Enterococcus

Question 20

What are the four bacilli gram +ve organsims need to know? [3]

Answer 20

Corynebacterium
Listeria
Bacillus: cereus (food pois); anthracis (anthrax)
Clostridium: tetani botulinum, difficile

Question 21

Which of the following is anaerobic?

Bacillus
Listeria
Clostridium
Corynebacterium

Answer 21

Which of the following is anaerobic?

Bacillus
Listeria
Clostridium
Corynebacterium

Question 22

Describe what would indicate on a gram stain that have a Streptococcus pneumoniae infection? [1]

Answer 22

Diplococci (come in pairs)

Question 23

What are the three cocci gram +ve organsims need to know? [3]

Answer 23

Staphylococcus
Streptococcus
Enterococcus

Question 24

Explain three immune defects that could predispose an individual to an pneuomococcal infection [3]

Answer 24

• HIV infection
• Hypogammaglobulinaemia (low levels of IgG due to B cells not being able to mature)
• Absent / non-functional spleen

Question 25

Give three reasons for an absent / non-functional spleen [3]

Answer 25

Congenital asplenia Traumatic removal Hyposplenism (eg sickle cell)

Question 26

Describe pathophysiology of pneuomococcal infection causing otitis media

Answer 26

**Streptococcus pneumoniae** first colonizes the mucosal surface of the human **nasopharynx** and can then infect the middle ear cavity via the **Eustachian tubes** Eustachian tube is more **horizontal** in children Easier to move from back of throat to middle ear Presents as **bulging tympanic membrane** If don’t treat then **tympanic membrane will rupture** and pus comes out **ear**

Question 27

Name two rheumatological implications of pneuomococcal pneuomonia infection

Answer 27

**Osteomyelitis** (inflammation in a bone and bone marrow, usually caused by bacterial infection) **Septic arthritis**

Question 28

Name 4 invasive features of Streptococcus pneumoniae infection

Answer 28

* Meningitis * Sepsis * Osteomyelitis * Septic arthritis * Peritonitis * Lobar pneumonia * Empyema

Question 29

Name the two most common presentations of Pneumococcal pneumonia [2]

Answer 29

1. **Lobar pneuomonia** 2. **Empyema** (a serious complication characterized by pus and bacteria in the pleural)

Question 30

How would you manage empyema caused by pneuomococcal pneuomonia? [2]

Answer 30

Chest drain Video-assisted thoracoscopic surgery (VATS)

Question 31

Name the two vaccinations for Streptococcus pneumoniae [2] and how many serotypes they protect agaisnt [2]

Answer 31

**Pneumococcal polysaccharide vaccine (PPV):** Penuomax - **covers 23 serotypes** **Pneumococcal conjugate vaccine (PCV):** Prevenar protects against **13 serotypes**

Question 32

Which pathogen causes A? [1]

Answer 32

**Corynebacterium dipetheria**

Question 33

Which pathogen cauese this symptom? [1]

Answer 33

**Neisseria meningitidis** - septic patient

Question 34

What is the most common cause of lobal pneumonia?

Answer 34

**Streptococcus pneumoniae**